Conventionally, when a pressure sensitive adhesive-backed tape is to be applied to an adherend such as, for example, a pressure sensitive adhesive-backed paint replacement film in tape form to a window sash frame of an automobile, generally, it is usual practice to utilize a tape application jig. This is because when a pressure sensitive adhesive tape is to be applied and adhered under pressure manually and carefully to a predetermined surface portion of the adherend so as not to give rise to puckering or inclusion of air bubbles, an excessive labor and time, in addition to the required skill, is needed for the tape application operation.
A tape application jig that is currently used in general is composed typically of an tape application unit for pressing and adhering the pressure sensitive adhesive tape to an adherend, a guide unit for maintaining the position and distance of the tape application jig relative to the adherend, and a tape holding unit for holding the pressure sensitive adhesive tape and feeding the adhesive tape to the tape application unit. In such a tape application jig, the position of the tape application jig relative to the adherend is generally maintained by holding the guide unit of the tape application jig in abutment against a predetermined surface portion of the adherend (for example, a sash frame). It is desirable that the guide unit and the tape application unit composing the tape application jig are disposed in axial alignment with each other or positioned in close proximity with each other.
Shape of an adherend, for example a sash frame of an automobile, has become increasingly diversified with recent diversification of vehicle type. A sash frame may be bent in its way or may be curved. Bent portion of a frame may be bent at a right angle or at an acute angle.
FIG. 1 is a view illustrating an example of usage of a typical prior art tape application jig 100 for applying a pressure sensitive adhesive tape 11 to a tape applying surface 20a of a sash frame 20 of an automobile having a bent portion 21. The sash frame 20 used in this example has a bent portion 21 with the angle θ which is substantially equal to 120 degrees. The tape application jig 100 is comprised of a tape application head 102, a tape holding member 106, and a jig guide 103 in the shape of a roller. The pressure sensitive tape 11 further comprises release paper 12 that protects the adhesive surface thereof prior to application.
The tape application jig 100 is first mounted to the end portion of the adherend 20, and application of the pressure sensitive tape is started from the straight portion. Then, the application jig 100 is moved in the direction of the arrow F and the tape application operation is continued. At the bent portion 21 of the adherend 20, the tape application operation cannot be continued as it is. Thus, typically, the application jig 100 is removed so that the orientation of the jig may be changed or a special jig guide for bent portion may be attached to the adherend. However, these works are complicated and not only increase the number of processing steps, but also may give rise to damages in the pressure sensitive adhesive tape. In the illustrated example, an advancing guide 109 is provided at the front end of the application jig 100 as shown in FIGS. 2A-2C. The advancing guide 109 is intended to facilitate smoother movement of the application jig 100.
More specifically, as shown in FIG. 2A, when the tape application jig 100 reaches the bent portion 21 of the adherend 20, the jig 100 is released from the tape application position, and the advancing guide 109 abuts against the adherend 20. Then, as shown in FIGS. 2B and 2C, the tape application jig 100 is moved along the bent portion 109 while maintaining the advancing guide 109 in abutment against the adherend 20. Although the pressure sensitive adhesive tape is not shown in FIGS. 2A-2C for the sake of simplicity of explanation, continuous application of the pressure sensitive tape is thus possible.
However, there is still room for improvement for the tape application jig described above with reference to FIGS. 1 and 2. For example, although the advancing guide is provided at the front end of the application jig, change of advancing direction is not easily performed, and great care needs to be given to the movement of the jig, leading to excessive labor and time required for the tape application operation. In addition, the jig needs to be released in the process of tape application, so that interruption of the tape application operation tends to give rise to a line of application mark on the surface of the tape or an inclusion of air bubble. In addition, conventional application jig has a drawback that the adhesive tape cannot be held reliably at the bent portion or curved portion of the adherend. Moreover, conventional tape application jig has a limit in the angle of the bent portion of adherend which permits the jig to be utilized, and the jig can be used only to such an adherend that has a bent portion 21 in FIG. 1 with the angle θ not less than 110 degrees.